/* mycp.c */
/* copies file named by argv[1] to file named by argv[2] */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define BUF_SZB 512

void an_error(char *s)
{
  printf("%s\n", s);
  exit(1);
}

void main(int argc, char *argv[])
{
  int from_fd,  to_fd;
  char buf[BUF_SZB];
  int bytes_read;

  if (argc != 3) {
    an_error("usage: mycp from-file to-file");
  }
  if ((from_fd = open(argv[1], O_RDONLY)) == -1) {
    an_error("couldn't open from-file for reading");
  }
  if ((to_fd = open(argv[2], O_WRONLY | O_CREAT,  S_IRUSR | S_IWUSR)) == -1) {
    an_error("couldn't create to-file for writing");
  }
  while ((bytes_read = read(from_fd, buf, BUF_SZB)) != 0) {
    if (write(to_fd, buf, bytes_read) == -1) {
      an_error("error writing to to-file");
    }
  }
  if (close(from_fd) == -1) {
    an_error("couldn't close from-file");
  }
  if (close(to_fd) == -1) {
    an_error("couldn't close to-file");
  }
  exit(0);
}

/* end of mycp.c */